This invention relates generally to a high speed, multi purpose, fluid dispensing apparatus and, specifically, to a printing apparatus of the type used to dispense ink for printing graphics images onto a target substraight.
This application is related to the copending application of Henry P. Taylor, et al., Ser. No. 441,285, filed Nov. 12, 1982, entitled MULTIPURPOSE FLUID DISPENSING APPARATUS. In that application, a multipurpose fluid dispensing apparatus, specially adapted for ink jet printing is shown which utilizes a technique in which ink drops are issued only on demand rather than in a continuous stream. A plurality of nozzels are provided through which ink can be intermittently, selectively ejected. Solenoid valves located between a source of pressurized ink and the ink nozzels are electrically opened and closed to dispense ink toward the target substraight. The ink nozzels are mounted in an orifice block which is integrally mounted on the case containing the valves, fluid tubing and electrical circuitry.
Although the orifice block could be removed to replace or repair damage to the nozzel openings, the design did not readily allow the substitution of nozzle blocks with different nozzle spacings. The height of the orifice block was limited based upon the associated height of the intergral print head case. Although two or more print heads could be stacked one upon the other with the nozzle orifices aligned, a space or gap existed between the top outermost nozzle orifice of the bottom print head and the bottom outermost nozzle orifice of the top print head. The design thus did not completely solve the problem posed by the need to increase character height and was not easily adapted to allow graphic printing which requires more nozzle orifice openings.
In U.S. Pat. No. 4,215,350, issued July 29, 1980, entitled INK JET PRINTING APPARATUS WITH TWO DIFFERENT JET SPACING, an apparatus is shown for printing characters which allows the height of the characters to be varied by means of a switch between two different groups of solenoid valves which control two groups of nozzels. The device depended upon electrical control for obtaining an increase in character height and was therefore complicated in design and expensive to manufacture.